Lead through terminal



Jan- 6 1943 l.. JOHNSTON LEAD THROUGH TERMINAL Filed Nov. 29, 1944 fllll:In n 1| Patented Jan. 6, 1948 UNITED STATES PATENT oEFlcE LEAD THROUGHTERMINAL Leith Johnston, Park Ridge, Ill.

Application November 29, 1944, Serial No. 565,617

The present invention relates to lead through terminals for establishingan electrical connection to an electrical device through a metallichousing. Terminals of this character have to be passed through the metalhousing in such a way as to make a sealed joint with the housing.

'It is the purpose of my invention to provide a lead through terminal byutilizing a metallic eyelet which can be sealed to the housing incombination with a rubber sleeve under compression and a terminal rodfor the rubber sleeve. It is a further purpose of my invention toprovide a novel method of securing a lead through terminal connection inpermanent sealed relation to the housing of an electrical device such asa transformer or condenser.

The Vnature and advantages of my invention will appear more fully fromthe following description and the accompanying drawing wherein apreferred form of the invention is shown. It should be understood,however, that the drawing and description are illustrative only andshould not be taken as limiting the invention except irlsofa-r as it islimited by the claim.

In the drawing:

Figure 1 is a view in side elevation of arubber sleeve employed in themaking of the lead through terminal;

Figure 2 is a longitudinal sectional view through a metallic eyeletwhich forms a part of the terminal;

Figure 3 is a sectional view taken longitudinally through the eyelet andshowing the rubber sleeve compressed therein;

Figure 4 is a view in side elevation oi a terminal rod before it iscombined with the assembly of Figure 3;

Figure 5 is a longitudinal sectional view through the terminal showingthe assembly of the terminal rod with the rubber sleeve and the metalliceyelet;

Figure 6 is a fragmentary sectional view 1 Claim. (Cl. 174-153) 2container in which the electrical device is housed. Many such devicesrequire a hermetically sealed housing. The present lead through terminalis constructed to prevent air passage where the electrical lead comesthrough the housing.

Referring now to Figures 1 to 6 inclusive, a

'I preferred method of making the terminal and mounting it in a housingwill be described. I show in Figure 1 a sleeve 10 which is constructedof a resilient compressible insulating material. The sleeve Illdesirably may be constructed of natural rubber or any of the knownsynthetic rubbers. One of the synthetic rubbers, neoprene, has beenfound particularly advantageous because of its cold flowcharacteristics. Some of the other synthetic rubbers also have a muchgreater resistance to deterioration by oil products than natural rubber,so for certain purposes they are to be, preferred. The sleeve I0 neednot be limited to rubber as there are other resilient materials such ascork that may be used. The sleeve I0 has a relatively small bore I I.

In Figure 2, I show a metal eyelet I2 which may be slightly taperedvbetween its ends. As shown there is just enough taper for the punch usedin drawing the eyelet from a blank. This eyelet has a flange I3 at oneend for mounting upon a housing. The other end I4 is plain. The eyeletmeets the flange with a flared portion to facilitate entry of the sleeveIl) into the eyelet. In carrying out my invention, the rst step is toassemble the sleeve i0 in the eyelet I2 to produce the combination shownin Figure 3. This assembly can be readily accomplished and it results ina slightk compression of the sleeve in the eyelet I2. The numeral I5indicates the restriction of the bore II due to the compression of thesleeve I0 in the eyelet.

through a portion'of a housing showing the lead Figure 8 is a viewsimilar to Figure 7 showing a i further modification; and

Figure 9 is a view similar to Figure 'I of a third modiiication of theterminal construction.

The lead through terminalof the present invention is adapted to be usedin connection with electrical devices such as transformers',condensers', switches and` the like to establish a seal A terminal rodI6 is next forced through the sleeve I D. In operation it is desirableto use a lubricant of some type to aid the passage of the rod. Thislubricant may be a material that will act as a cement between the rodand the sleeve IU after it has served its purpose as a means of reducingfriction due to pressing the rod through the sleeve. The rod I6 will benoted as much larger in diameter than the bore II of the sleeve so thatit expands the rubber sleeve I0. The expansion, however, cannot takeplace within the eyelet andthe forcing of the terminal rod through theeyelet puts the sleeve within the eyelet under compression radially ofthe eyelet and under tension axially of the eyelet. The tension iseffective to hold the end portions of the sleeve against around theelectrical leads that pass through a the ends of the eyelet. Theportions Illa and Illb of the sleeve I are expanded outward until theyoverlap the ends ot the eyelet I2. An eective sealing is thusaccomplished so that no air can pass through the eyelet I2,

. The next steps in the assembly are to form the ends of the rod I8 sothat they may be used for attaching conductors. Figure 6 shows the rodends as flattened and apertured to form eyelets Il and I8. Figure 6 alsoillustrates the manner in which-the terminal assembly is secured in ahousing. The housing is indicated at I9. It is provided with an aperturewhich is large enough to receive the portion I0b of the sleeve l0.According to the preferred practice, I also provide a depression beingof such size as to seat the flange I3 of the eyelet I2. The eyelet I2is,

soldered to the housing I9 by flowing solder 2Ia around the ilange I3 insuilicient quantitiesto make a good seal.

Figure 7 of the drawing illustrates a slightly varied form of theinvention. The variation consists in the following features. An eyelet22 is utilized. This'eyelet may be slightly tapered in diameter asshown, or straight. It is also provided with a flange 24 which may bemounted like the flange I3 to the housing or placed against the innersurface of the housing as illustrated in Figure '7. The eyelet 22extends through an opening 23 in the housing and has its upper end 25flared outward slightly to facilitate forcing the sleeve Ill therein. Inthis form oi' the invention a different type of terminal rod 26 isshown. This terminal rod had a cylindrical portion which can be forcedinto the sleeve I0 to cause the sleeve to expand. The terminalv rod 26has a threaded'terminal portion 21 and a. hexagonal portion 28 adjacentto the portion 21 to serve as a means for holding the rod when a wireterminal nut is threaded on the Portion 21 and to form one end abutmentfor the sleeve I0. After the terminal rod 26 is forced through thesleeve I0 and the eyelet 22, a washer 29 is placed thereon and thesleeve is compressed endwise between the parts 28 and 29. The rod 2l isupset as indicated at 30 so as to hold the sleeve I0 under compression.The end of the rod 26 can be flattened as shown at 3| and apertured inthe same operation that upsets the portions 30.

In soldering eyelets I2 and 22 to the housing I9, there is an additionaladvantage obtained toward sealing the device. The temperature of thesolder used is in the neighborhood of 500 F. The rubber vulcanizes atsomewhat above 300 F. There is enough heat loss between the solder andthe rubber sleeve I0 to prevent over-heating of the rubber, but at thesame time,thel heat conduction through the eyelet I2 causes thevulcanization and sticking of the rubber to the eyelet I2 and to acertain extent to the terminal rod I6. Therefore, in the final assemblyan excellent seal is obtained.

The device shown in Figure 8 is essentially similar to that shown inFigures 1 to 6, except that a new terminal rod 32 is used. 'Ihe mannerof mounting the terminal rod 32 in the sleeve I0 and the eyelet I2 isthe same as the manner of completing the device shown in Figures 1 to 6.The terminal rod l2 is made with reduced end portions 32a and 32h thatare smaller than the bore ofthe sleeve I0 so they can be bent and mayhave considerable freedom of movement with respect to the sealed part inthe eyelet I2.

Figure 9 illustrates a type of tubular terminal rod assembled in thesame fashion as the terminal rod I6 was membled with a sleeve Il and aneyelet I2. In Figure 9 the terminal rod 33 is hollow and has both endsflanged over as shown at 3l and 36, to mount an angular terminal strip3l, and a washer 31. The sleeve Il) is compressed between the members 35and 31 so as to make it bulge out over the ends of the eyelet I2. Inthis form of device the wiring 38 is led out through the rod 33 andwrapped around the strips 35. The wire is sealed in place by use ofsolder indicated at 39 which will also run into the hollow terminal rod33 and seal it. If there is any doubt about the solder 39 sealing thehollow rod 33, the interior of the rod may be illled with a sealingcomposition after the lead 38 is drawn through and before the solderingis done.

It is believed that the foregoing description and the accompanyingdrawing will enable those skilled in this art to utilize the inventionshown and described.

Having thus described my invention, I claim:

A method of prOducing a hermetlcally sealed lead through terminal whichcomprises forcing a sleeve of rubber through a metal eyelet, thenforcing a, conductor rod much larger in cross section than the bore ofthe sleeve, through the assembled sleeve and eyelet, then soldering saideyelet to a supporting metal wall and thereby vulcanizing the rubber tothe eyelet.

LEITH JOHNSTON.

REFERENCES CITED The following references are of record in the NumberName Date 1,852,454 Foster Apr. 5, 1932 1,899,591 Segar Feb. 28, 19332,014,004 Mershon Sept. 10, 1935 2,052,700 De Lange Sept. 1, 19362,138,660 Mann Nov. 29, 1938 2,167,286 Theobald July 25, 1939 2,169,967Smith Aug. 15, 1939 2,170,718 Humphries Aug. 22, 1939 2,181,860 AdkinsonDec. 5, 1939 2,219,940 Ritz-Woller Oct. 29, 1940 2,223,153 Seifer NOV.26, 1940 2,266,523 Waterman Dec. 16, 1941 2,368,548 Kalstein Jan. 30,1945 2,387,630 Weakley Oct. 23, 1945

